Chemical characterization by HPLC-ESI-Q-TOF-MS/MS and evaluation of the gastroprotective and antinociceptive activities of the ethanolic extract of Rhynchospora nervosa (Vahl) Boeckeler (Cyperaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Rhynchospora nervosa is widely used by traditional Brazilian communities to treat inflammation. However, despite its ethnomedicinal relevance, this native and endemic species still lacks scientific investigation regarding its potential use in the prevention of gastric ulcers or inflammatory pain management. In addition, its chemical constituents and pharmacological mechanisms remain poorly understood. AIM OF THE STUDY: This study aimed to characterize the chemical composition and evaluate the gastroprotective and antinociceptive activities of the ethanolic extract obtained from the aerial parts of R. nervosa (EERn). MATERIALS AND METHODS: The chemical composition of EERn was analyzed by HPLC-ESI-Q-TOF-MS/MS. Acute oral toxicity was evaluated in female Swiss mice over 14 days. Gastroprotective activity was evaluated using an absolute ethanol-induced gastric ulcer model. Antinociceptive activity was tested using acetic acid-induced writhing and formalin models. Mechanistic studies were performed using pharmacological antagonism assays. RESULTS: The compounds apigenin-C-hexoside and luteolin-C-hexoside, which exhibited the most intense signals under the analytical conditions used, were annotated in the EERn and reported here for the first time in the genus Rhynchospora. In the acute oral toxicity test, no adverse effects were observed in Swiss mice treated with a single dose of 2000 mg/kg of EERn, suggesting the preliminary biological safety of the plant extract. Regarding antiulcer activity, EERn at doses of 200 and 400 mg/kg showed a protective role against the deleterious effects of ethanol on the gastric mucosa of mice and no lesions were observed. Mice treated with 200 and 400 mg/kg of EERn showed a significant reduction in abdominal writhing by up to 72% and 97.4%, respectively. Pre-administration of naloxone attenuated the antinociceptive response observed for EERn (400 mg/kg) and the positive control morphine (10 mg/kg) in mice. These findings suggest a possible involvement of the opioid system in the antinociception promoted by the extract. CONCLUSION: The ethanolic extract of R. nervosa has demonstrated promising gastroprotective and antinociceptive activities, together with preliminary evidence of biological safety in Swiss mice. The results suggested that the flavonoid glycosides annotated in EERn may contribute to the biological activities observed in this study.